In the ad, Chico equates the Emanuel's plan -- which he calls "The Rahm Tax" -- to the highly unpopular and controversial one percent sales tax pushed through in 2008 by then-Cook County President Todd Stroger.

"If you thought the Stroger sales tax was a killer, you’ll hate the Rahm Tax," a narrator says in the ad.

Emanuel responded to the ad after accepting the endorsement of the Sierra Club.

"My view is to attack the problems that are facing the city of Chicago, not attack each other," said Emanuel. "It's been over a week since Gery decided to announce any new ideas, except for criticizing an idea he once agreed with."

The Chico campaign, however, pointed to a proposal to bring the Super Bowl to Chicago that was floated last week.